Development of a Radiation-Tolerant Component for the Quench Protection System

Oliver Bitterling

Introduction to the QPS Radiation damage in electronic systems Construction of radiation tolerant systems Radiation test and their results Conclusion and outlook

Outline

Detection of loss of the superconductivity of the LHC Magnets

Loss of local superconductivity is called a Quench

Undiscovered Quenches lead to serious damage to the accelerator

Discovered Quenches can be mitigated without damage

What is the Quench Protection System (QPS)?

The increase of availability is an important goal of the redesign of the QPS

QPS must not overlook any quenches but should only produces as few as possible false triggers

QPS is located close to the accelerator and is subjected to certain amounts of stray radiation

Radiation can cause damage and random errors inside electronic systems

Increase of LHC Availability

Statistical Radiation Errors High doses of

high energy radiation can destroy semiconductor lattice

Even low doses can cause statistical radiation errors

QPS for the 600 A Magnets

Two high resolution ADCs are necessary to measure the current and voltage with the necessary precision

High Resolution Measurement of Current and Voltage

Some components are specially constructed in a way that makes them highly resistant to radiation

Such hardware is usually used for space applications like satellites

Radiation Hardened Components

Problems:Very Expensive!!!Not available

“Components of the shelf” (COTs) differ widely in their resistance to radiation

COTs have to be tested a irradiation facilities to determine how the react to radiation

The ADC for our project was tested at the Paul-Scherrer-Institute (PSI)

A future radiation test will be conducted at the new irradiation facility CHARM at CERN

Radiation Tolerant Hardware

ADC Output of a Magnet Ramp

Typical voltage and current during a magnet ramp as stimulus

ADC survives even after high doses of radiation

Output signal is corrupted

Multi Sample Error

Error Rates

Typical irradiation level of 1 Gy every year (later 10 Gy)

System consists out of 200 cards with two ADCs

Resulting error rate of 1 error every 3 days

Countermeasures

After countermeasures error rate decreases to 1 error every year

Final version should be able to eliminate all errors

Error Rates after Countermeasures

The QPS has to be very precise to prevent damage and increase beam time

Radiation can disturb the operation of the QPS and lead to premature beam dumps

Using tolerant hardware and error specific countermeasures it is possible to develop systems able to work under radiation

Latest measurements have shown that the system is already sufficiently stable but there are still ways to improve

Conclusions and Outlook

Thank you for your Attention

Questions?

Disturbances in the signal can be mitigated by using a combination of several digital filters

Normal ADC stops can be tolerated by the system

Longer stops could be prevented by automatic restart of the ADC

Configuration errors can be fixed by continuous monitoring of the configuration register and fixing any errors

Countermeasures

Some Results from the Irradiation Campaign

Some Results from the Irradiation Campaign

Control System and what are FPGAs

FPGAs that store their configuration inside SRAM cells are highly vulnerable to radiation effects

A possible method to allow them to function is to constantly read out the configuration, check for corruption and fix as necessary

Flash based FPGAs are more tolerant to radiation

How to protect FPGAs

Flash based FPGAs

Triplication protects the algorithm by creating 3 instances of every part

If only one part is corrupted a majority vote will only transmit the correct result

Protecting the Algorithm